Electric motors have been used to operate motor vehicles. The electric motors are connected to conventional power transmissions and clutch units to operate motor vehicles. Permanent magnet couplings have been utilized to apply a load on a motor after the motor is at full speed.
K. J. Lamb in U.S. Pat. No. 5,668,424 discloses a magnetic coupler having a magnetic disk supporting permanent magnets located adjacent an electroconductive plate. The magnetic disk is free to rotate as an independent idler. An electro conductive plate mounted on a spline is moved relative to the magnetic disk to control the air gap and magnetic flux between the magnetic disk and the electroconductive plate to provide speed adjustment of the load while the motor operates at constant speed.
V. Dombrovski et al in U.S. Pat. No. 6,054,788 discloses a magnetic power transmission having first and second shafts drivably connected with a plurality of first and second permanent magnets. The magnets have alternating polarity magnetic surfaces. The first and second magnets are separated by an air gap so that rotation of one of the magnets urges synchronous rotation of the other magnets.